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In this study, ultra-small nickel nanoparticles on NiFe 2 O 4 (Ni@NiFe 2 O 4) and Ni@NiFe 2 O 4 /ZnO magnetic nanocomposites were synthesized and utilized for the solar light-driven photocatalytic degradation of cefadroxil. The drug cefadroxil is widely used to treat bacterial infections and cefadroxil is a non-biodegradable pharmaceutical compound detected in the groundwater sources because of its low removal efficiency. The Raman active phonon at 540 cm−1 confirms the presence of Ni nanoparticles at the surface of NiFe 2 O 4 /ZnO. DR-UV-Vis analysis exhibited surface plasmon resonance at 350 nm for ultra-small nickel nanoparticles. The observed optical bandgap values for Ni@NiFe 2 O 4 and NiFe 2 O 4 /ZnO are 1.2 eV and 2.43 eV, respectively. Which indicates that these magnetic nanocomposites can be utilized for the mineralization of cefadroxil (β-lactam antibiotic) under ambient environmental conditions. The efficiency was determined by the direct solar light driven photocatalytic oxidation of cefadroxil in the presence and absence of peroxymonosulphate (PMS). The experimental findings exhibits that ∼95 % of cefadroxil (CDL) was eliminated by the ultra-small Ni@NiFe 2 O 4 /ZnO within 60 min (k = 7.5 × 10−4 s−1) of direct solar light irradiation. Further, the addition of PMS enhanced the photodegradation to achieve 100 % cefadroxil oxidation within 40 min (k = 25 × 10−4 s−1) of direct sunlight. The efficiency of the nanocatalyst was compared with controlled experiments and was found to be Fe 2 O 3 < ZnO < TiO 2 (P25) < Ni@NiFe 2 O 4 < Ni@NiFe 2 O 4 /ZnO under absence and presence of PMS. Moreover, ultra-small Ni@NiFe 2 O 4 /ZnO nanophotocatalyst were stable up to 3 consecutive cycles. [ABSTRACT FROM AUTHOR]

Methicillin-resistant Staphylococcus aureus (MRSA) mastitis poses a significant threat to dairy herds worldwide, given its resistance to methicillin and other β-lactam antibiotics, which often leads to treatment failure. Consequently, there is an urgent need for safe and effective alternative therapeutic approaches. Recent investigations have highlighted the potential of baicalein, a natural flavonoid known for its potent anti-inflammatory and antibacterial properties, especially its synergistic effects with β-lactam antibiotics against MRSA. However, the limited solubility and bioavailability of baicalein hinder its biomedical utility. The present study assessed the therapeutic efficacy of encapsulated baicalein in chitosan, forming a tricomplex with a β-lactam antibiotic, using a murine model of MRSA-induced mastitis. The experimental design comprised seven groups, each consisting of six mice. We evaluated the ability of various treatment regimens to mitigate histopathological alterations and bacterial burden induced by MRSA infection, aiming to elucidate underlying mechanisms. Our results revealed that tricomplex treatment significantly reduced bacterial load in mammary tissue and preserved tissue integrity, resulting in decreased inflammatory responses post-MRSA inoculation. In addition, tricomplex treatment markedly reduced mean leukocyte and neutrophil counts in blood and suppressed the matrix metalloproteinase-9 (MMP-9) concentration and C-reactive protein (CRP) response. Notably, the synergistic interaction between baicalein and amoxicillin was particularly pronounced. Our findings suggest that chitosan-encapsulated baicalein combined with a β-lactam antibiotic holds promise as a therapeutic option for MRSA-induced mastitis. Further investigations, particularly in target animal species, are warranted to comprehensively evaluate its clinical feasibility.

Objective To investigate the relationships between serum albumin (ALB) levels and the risk of treatment failure with β-lactam antibiotics in elderly patients with community-acquired pneumonia (CAP) as well as the predictive threshold and efficacy. Methods According to serum ALB levels on the day of admission, 86 elderly patients with CAP were divided by quartiles into Q1 group, Q2 group, Q3 group, and Q4 group. All the patients received β-lactam antibiotics, and the treatment response rate was compared between groups. The data on age, sex, comorbidities, laboratory indicators, and the CURB-65 severity score were collected. To analyze the association of serum ALB levels with the risk of β -lactam antibiotic failure, we performed univariable Logistic regression analyses to select significant variables, and then included them along with age and sex as confounding factors in a multivariable Logistic regression model for further analysis. We constructed a restricted cubic spline (RCS) model to determine the serum ALB threshold for the risk of non-response to β-lactam antibiotics. Using the threshold as the grouping criterion, a stratified multivariable Logistic regression analysis was conducted to analyze the relationships between serum ALB levels and the risk of β-lactam antibiotic failure. Results The serum ALB level of the 86 patients with CAP was (29. 0±5.1) g/L. Fifty-nine patients responded to β-lactam antibiotics, while the remaining 27 patients did not. The response rates in the Q1, Q2, Q3, and Q4 groups were 39. 13%, 76. 19%, 71. 43%, and 91. 48%, respectively. The proportion of patients with a history of chronic obstructive pulmonary disease in the Q1 group was significantly lower than those in the other groups (all P<0. 05). The Q4 group showed a significantly lower neutrophil count and a significantly lower C-reactive protein level than the other groups (all P<0. 05). Serum ALB level was negatively associated with the risk of β-lactam antibiotic failure in the elderly patients with CAP: the odds ratio (OR) and 95% confidence interval (CI) were 0. 18（0.04-0.78) in the Q2 group, 0. 19（0. 04-0. 93) in the Q3 group, and 0. 07（0. 01-0. 46) in the Q4 group (P for trend=0. 019). The RCS analysis showed an L-shaped non-linear relationship between serum ALB level and the risk of non-response to β-lactam antibiotics, and the serum ALB threshold associated with the risk of treatment failure was 30 g/L. When serum ALB levels were ≤30 g/L, the risk of non-response per standard deviation increase in ALB decreased by 82% (OR=0.18, 95% CI: 0.04-0.58, P<0. 05); when serum ALB levels were >30 g/L, there was no significant relationship between serum ALB level and the risk of β-lactam antibiotic failure (P>0. 05). Conclusions Serum ALB level is negatively correlated with the risk of β-lactam antibiotic failure in elderly patients with CAP. The serum ALB threshold for the risk of non-response to β-lactam antibiotics in elderly CAP patients is 30 g/L, and there is a higher risk of β-lactam antibiotic failure for elderly CAP patients with the serum ALB level within 30 g/L. [ABSTRACT FROM AUTHOR]

ABSTRACT: β-Lactam antibiotics are one of the most clinical importance in human and veterinary medicine because they are used for both preventive and therapeutic purposes against several gram-positive, gram-negative, and anaerobic organisms. In this study, it was confirmed that β-lactams (81.1%) were found to be significantly prescribed the most among 74 farms in 5 integrated broiler operations, and single prescription (84.6%), 2-day (41.5%) or 3-day (40.0%) administration, and 15 to 22 d of age (67.7%) administration was significantly higher in the farms (P < 0.05). Among the E. coli isolated from 74 farms in 5 integrated broiler operations, β-lactam-resistant E. coli isolates were detected more frequently in fecal sample (94.6%) than in dust sample (60.8%) (P < 0.05). The prevalence of MDR in β-lactam-resistant isolates, ranging from 88.1 to 96.5%, was significantly higher than that in non–β-lactam-resistant isolates (P < 0.05), without significant differences among operations. Of 466 β-lactam-resistant isolates, 432 (92.7%) isolates harbored β-lactamase genes. The non–extended-spectrum β-lactamase (ESBL) gene blaTEM-1 (81.8%) showed the highest prevalence among isolates, followed by the non-ESBL gene blaTEM-135 (6.4%) (P < 0.05). Five ESBL genes, SHV-12, OXA-1, CTX-M-27, CTX-M-55, and CTX-M-65, were found in 0.9 to 6.0% of the isolates. The pAmpC gene blaCMY-2 was detected in 17 isolates (3.6%). These results suggest that feces and dust are important reservoirs of antimicrobial-resistant bacteria, highlighting the need to strengthen farm management regulations, such as cleaning, disinfection, and litter disposal and to reduce the use of antibiotics in broiler operations.

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β-lactamase, a kind of hydrolase in multi-drug resistant pathogens, can hydrolyze β-lactam antibiotics and make these kinds of antibiotics invalid. Small-molecular inhibitors about the enzyme and their mechanism are widely investigated but they may result in unavoidable adverse reactions and drug-resistance. Herein, we propose a new therapeutic strategy of Chinese materioherbology, in which herbal medicine or traditional Chinese medicinal herbs can be employed as biological functional materials or refreshed/excited by means of materialogy. Natural tea nanoclusters (TNCs) were extracted from tea to inhibit β-lactamase. Different from the mechanism of small-molecular inhibitors inhibiting enzymes by binding to the corresponding active sites, the TNCs as a cap cover the protein pocket and create a spatial barrier between the active sites and antibiotics, which was named “capping-pocket” effect. TNCs were combined with amoxicillin sodium (Amo) to treat the methicillin-resistant Staphylococcus aureus (MRSA) pneumonia in mice. This combinatorial therapy remarkably outperforms antibiotic monotherapy in reducing MRSA infections and the associated inflammation in mice. The therapeutic strategy exhibited excellent biosafety, without any side effects, even in piglets. Hence, TNCs have great clinical value in potentiating β-lactam antibiotic activity for combatting multi-drug resistant pathogen infections and the ''pocket capping'' effect can guide the design of new enzyme inhibitors in near future.

ABSTRACT The emergence of antibiotic resistance has led to a global crisis for the physician to handle infection control issues. All antibiotics, including colistin, have lost efficiency against emerging drug-resistant bacterial strains due to the production of metallo-β-lactamases (MBLs) and serine-β-lactamases (SBLs). Therefore, it is of the utmost importance to design inhibitors against these enzymes to block the hydrolytic action against antibiotics being used. Although various novel β-lactamase inhibitors are being authorized or are under clinical studies, the coverage of their activity spectrum does not include MDR organisms expressing multiple classes of β-lactamases at a single time. This study reports three novel broad-spectrum inhibitors effective against both SBLs and MBLs. Virtual screening, molecular docking, molecular dynamics simulations, and an in silico pharmacokinetic study were performed to identify the lead molecules with broad-spectrum ability to inhibit the hydrolysis of β-lactam. The selected compounds were further assessed by in vitro cell assays (MIC, 50% inhibitory concentration [IC50], kinetics, and fluorescence against class A, B, and C type β-lactamases) to confirm their efficacies. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay was performed to check the toxicity of screened lead molecules. All three selected inhibitors were found to reduce MIC and showed good affinity against all the SBLs and MBLs produced by class A, B, and C type β-lactamases. These nontoxic novel non-β-lactam broad-spectrum inhibitors bind to the active site residues of selected β-lactamases, which are crucial for β-lactam antibiotic hydrolysis. These inhibitors may be proposed as a future drug candidate in combination with antibiotics as a single formulation to control infection caused by resistant strains. Hence, this study plays a significant role in the cure of infections caused by antibiotic-resistant bacteria. IMPORTANCE Several inhibitors for usage in conjunction with antibiotics have been developed. However, to date, there is no commercially available broad-spectrum β-lactamase inhibitor that targets both MBLs and SBLs. Here, we showed three novel broad-spectrum inhibitors with promising results through computational techniques and in vitro studies. These inhibitors are effective against both SBLs and MBLs and hence could be used as future drug candidates to treat infections caused by multidrug-resistant bacteria producing both types of enzymes (SBLs and MBLs).

In this study, a multi-residue determination method of QuECHERS combined with UHPLC-MS/MS was developed to determine nine β-lactam antibiotics (penicillin G, amoxicillin, ampicillin, cephalexin, cefquinome, ceftiofur, cefazolin, cephapirin, cefuroxime) in aquaculture products. All the nine β-lactam antibiotics exhibited excellent linearity within the range of 2.0–200 ng/mL (cefuroxime: 5.0–200 ng/mL, r greater than 0.999), while the limits of detection (LODs) and quantification (LOQs) were 2.0–5.0 μg/kg and 5.0–10.0 μg/kg, respectively. The recoveries of this method in five aquaculture products (Penaeus Orientalis, Cyprinus Carpio, Channa Argus, Aristichthys Nobilis, and Ctenopharyngodon Idella) ranged from 85.4% to 113.3% and the intra-day and inter-day precisions (%RSDs) were less than 15%. The results suggested the feasibility of this method as a rapid, simple, and accurate approach for determining the residues of the β-lactam antibiotics in aquaculture products.

Mingjia Peng,1,2 Renru Han,1,2 Yan Guo,1,2 Yonggui Zheng,1,2 Feifei Yang,1,2 Xiaogang Xu,1,2 Fupin Hu1,2 1Institute of Antibiotics, Huashan Hospital, Fudan University, Shanghai, People’s Republic of China; 2Key Laboratory of Clinical Pharmacology of Antibiotics, Ministry of Health, Shanghai, People’s Republic of China; 3National Clinical Research Centre for Aging and Medicine, Huashan Hospital, Fudan University, Shanghai, People’s Republic of ChinaCorrespondence: Fupin Hu; Xiaogang Xu Email hufupin@fudan.edu.cn; xuxiaogang@fudan.edu.cnBackground: The spread of KPC-producing Enterobacteriaceae has triggered a global public health concern, with KPC-2-positive strains being the most prevalent in China. We hereby studied the in vitro combined inhibitory activities of three kinds of β-lactam antibiotics and clavulanic acid at different concentrations against blaKPC-2-positive Klebsiella pneumoniae to explore the antimicrobial characteristics of these combinations and alternative therapeutic regimens for infections caused by blaKPC-2-positive K. pneumoniae strains.Materials and Methods: In this study, 153 clinically isolated blaKPC-2-positive K. pneumoniae strains from 19 provinces in China were collected from 2016 to 2018. Antimicrobial susceptibility testing of imipenem/clavulanic acid, meropenem/clavulanic acid, ceftazidime/clavulanic acid, and each antimicrobial agent alone was performed by broth microdilution technique according to the CLSI guidelines. The concentration ratios of β-lactam antibiotics to clavulanic acid were as follows: 1:1, 1:2, 1:4, 1:8, 1:16, 1:32. The antimicrobial susceptibility of the combinations was determined according to the breakpoints of Imipenem, meropenem, and ceftazidime established by the CLSI directives for Enterobacteriaceae.Results: The MICs of all three combinations gradually declined with increments in the proportion of clavulanic acid in the regimens, and the most significant decline in the MIC50 and MIC90 was seen in combinations at the concentration ratio of 1:1 (also 1:2 for meropenem/clavulanic acid). When the concentration of clavulanic acid was restricted to 4 mg/L, the susceptibility of more than 70% of the isolates to the regimens could be restored with imipenem MIC 2– 4 mg/L, meropenem MIC 2– 8 mg/L or ceftazidime MIC 8mg/L. However, the percentage decreased to 30 to 40% when the initial MIC level was higher.Conclusion: The highest combined inhibitory activity of β-lactam antibiotics/clavulanic acid at low concentration ratios against blaKPC-2-positive K. pneumoniae may offer a new way to optimize the effects of these antimicrobial regimens.Keywords: KPC, Enterobacteriaceae, combined inhibitory activity, clavulanic acid, β-lactam antibiotic

Penicillins and cephalosporins are the most important class of beta (β) lactam antibiotics, accounting for 65% total antibiotic market. Penicillins are produced by Penicillium rubens (popularly known as P. chrysogenum) were used to synthesize the active pharmaceutical intermediate (API), 6-aminopenicillinic acid (6-APA) employed in semisynthetic antibiotic production. The wild strains produce a negligible amount of penicillin (Pen). High antibiotic titre-producing P. chrysogenum strains are necessitating for industrial Pen production to meet global demand at lower prices. Classical strain improvement (CSI) approaches such as random mutagenesis, medium engineering, and fermentation are the cornerstones for high-titer Pen production. Since, Sir Alexander Fleming Discovery of Pen, great efforts are expanded to develop at a commercial scale antibiotics producing strains. Breakthroughs in genetic engineering, heterologous expression and CRISPR/Cas9 genome editing tools opened a new window for Pen production at a commercial scale to assure health crisis. The current state of knowledge, limitations of CSI and genetic engineering approaches to Pen production are discussed in this review. [ABSTRACT FROM AUTHOR]

Abstract Methicillin-resistant Staphylococcus aureus (MRSA) strains are distinct from general Staphylococcus strains with respect to the composition of the membrane, ability to form a thicker biofilm, and, importantly, ability to modify the target of antibiotics to evade their activity. The agr gene is an accessory global regulator of gram-positive bacteria that governs virulence or resistant mechanisms and therefore an important target for the control of resistant strains. However, the mechanism by which agr impacts resistance to β-lactam antibiotics remains unclear. In the present study, we found the Δagr mutant strain having higher resistance to high concentrations of β-lactam antibiotics such as oxacillin and ampicillin. To determine the influence of variation in the microenvironment of cells between the parental and mutant strains, fatty acid analysis of the supernatant, total lipids, and phospholipid fatty acids were compared. The Δagr mutant strain tended to produce fewer fatty acids and retained lower amounts of C16, C18 fatty acids in the supernatant. Phospholipid analysis showed a dramatic increase in the hydrophobic longer-chain fatty acids in the membrane. To target membrane, we applied several surfactants and found that sorbitan monolaurate (Span20) had a synergistic effect with oxacillin by decreasing biofilm formation and growth. These findings indicate that agr deletion allows for MRSA to resist antibiotics via several changes including constant expression of mecA, fatty acid metabolism, and biofilm thickening.

Nonribosomal peptide synthetases (NRPSs) are responsible for the production of important biologically active peptides. The large, multidomain NRPSs operate through an assembly line strategy in which the growing peptide is tethered to carrier domains that deliver the intermediates to neighboring catalytic domains. While most NRPS domains catalyze standard chemistry of amino acid activation, peptide bond formation, and product release, some canonical NRPS catalytic domains promote unexpected chemistry. The paradigm monobactam antibiotic sulfazecin is produced through the activity of a terminal thioesterase domain of SulM, which catalyzes an unusual β-lactam-forming reaction in which the nitrogen of the C-terminal N-sulfo-2,3-diaminopropionate residue attacks its thioester tether to release the monobactam product. We have determined the structure of the thioesterase domain as both a free-standing domain and a didomain complex with the upstream holo peptidyl-carrier domain. The position of variant lid helices results in an active site pocket that is quite constrained, a feature that is likely necessary to orient the substrate properly for β-lactam formation. Modeling of a sulfazecin tripeptide into the active site identifies a plausible binding mode identifying potential interactions for the sulfamate and the peptide backbone with Arg2849 and Asn2819, respectively. The overall structure is similar to the β-lactone-forming thioesterase domain that is responsible for similar ring closure in the production of obafluorin. We further use these insights to enable bioinformatic analysis to identify additional, uncharacterized β-lactam-forming biosynthetic gene clusters by genome mining., Competing Interests: Conflict of interest The authors declare that they have no conflicts of interest with the contents of this article., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

BackgroundIt remains largely unknown how physicochemical properties of hydrolysed infant formulas influence their allergy preventive capacity, and results from clinical and animal studies comparing the preventive capacity of hydrolysed infant formula with conventional infant formula are inconclusive. Thus, the use of hydrolysed infant formula for allergy prevention in atopy-prone infants is highly debated. Furthermore, knowledge on how gut microbiota influences allergy prevention remains scarce.ObjectiveTo gain knowledge on (1) how physicochemical properties of hydrolysed whey products influence the allergy preventive capacity, (2) whether host microbiota disturbance influences allergy prevention, and (3) to what extent hydrolysed whey products influence gut microbiota composition.MethodsThe preventive capacity of four different ad libitum administered whey products was investigated in Brown Norway rats with either a conventional or an amoxicillin-disturbed gut microbiota. The preventive capacity of products was evaluated as the capacity to reduce whey-specific sensitisation and allergic reactions to intact whey after intraperitoneal post-immunisations with intact whey. Additionally, the direct effect of the whey products on the growth of gut bacteria derived from healthy human infant donors was evaluated by in vitro incubation.ResultsTwo partially hydrolysed whey products with different physicochemical characteristics were found to be superior in preventing whey-specific sensitisation compared to intact and extensively hydrolysed whey products. Daily oral amoxicillin administration, initiated one week prior to intervention with whey products, disturbed the gut microbiota but did not impair the prevention of whey-specific sensitisation. The in vitro incubation of infant faecal samples with whey products indicated that partially hydrolysed whey products might confer a selective advantage to enterococci.ConclusionsOur results support the use of partially hydrolysed whey products for prevention of cow’s milk allergy in atopy-predisposed infants regardless of their microbiota status. However, possible direct effects of partially hydrolysed whey products on gut microbiota composition warrants further investigation.

Background: It remains largely unknown how physicochemical properties of hydrolysed infant formulas influence their allergy preventive capacity, and results from clinical and animal studies comparing the preventive capacity of hydrolysed infant formula with conventional infant formula are inconclusive. Thus, the use of hydrolysed infant formula for allergy prevention in atopy-prone infants is highly debated. Furthermore, knowledge on how gut microbiota influences allergy prevention remains scarce. Objective: To gain knowledge on (1) how physicochemical properties of hydrolysed whey products influence the allergy preventive capacity, (2) whether host microbiota disturbance influences allergy prevention, and (3) to what extent hydrolysed whey products influence gut microbiota composition. Methods: The preventive capacity of four different ad libitum administered whey products was investigated in Brown Norway rats with either a conventional or an amoxicillin-disturbed gut microbiota. The preventive capacity of products was evaluated as the capacity to reduce whey-specific sensitisation and allergic reactions to intact whey after intraperitoneal post-immunisations with intact whey. Additionally, the direct effect of the whey products on the growth of gut bacteria derived from healthy human infant donors was evaluated by in vitro incubation. Results: Two partially hydrolysed whey products with different physicochemical characteristics were found to be superior in preventing whey-specific sensitisation compared to intact and extensively hydrolysed whey products. Daily oral amoxicillin administration, initiated one week prior to intervention with whey products, disturbed the gut microbiota but did not impair the prevention of whey-specific sensitisation. The in vitro incubation of infant faecal samples with whey products indicated that partially hydrolysed whey products might confer a selective advantage to enterococci. Conclusions: Our results support the use of partially hydrolysed whey products for prevention of cow's milk allergy in atopy-predisposed infants regardless of their microbiota status. However, possible direct effects of partially hydrolysed whey products on gut microbiota composition warrants further investigation. [ABSTRACT FROM AUTHOR]

• PEI-modified HNTs-based hybrid silica monolith was prepared. • The monolith showed a large adsorption capacity of hydrophilic cefoperazone. • The monolith was used as a sorbent for spin tip solid-phase extraction. • The tip effectively purified sulbactam, cefoperazone and cefuroxime in whole blood. • The determination of the analytes was accurate, reproducible and sensitive. In this study, we proposed a novel method utilizing polyethyleneimine (PEI)-modified halloysite nanotubes (HNTs)-based hybrid silica monolithic spin tip to analyze hydrophilic β-lactam antibiotics and β-lactamases inhibitors in whole blood samples for the first time. HNTs were incorporated directly into the hybrid silica monolith via a sol-gel method, which improved the hydrophilicity of the matrix. The as-prepared monolith was further modified with PEI by glutaraldehyde coupling reaction. It was found that the PEI-modified HNTs-based hybrid silica monolith enabled a large adsorption capacity of cefoperazone at 35.7 mg g−1. The monolithic spin tip-based purification method greatly reduced the matrix effect of whole blood samples and had a detection limit as low as 0.1 − 0.2 ng mL−1. In addition, the spiked recoveries of sulbactam, cefuroxime, and cefoperazone in blank whole blood were in the range of 89.3–105.4 % for intra-day and 90.6–103.5 % for inter-day, with low relative standard deviations of 1.3–7.2 % and 4.9–10.5 %, respectively. This study introduces a new strategy for preparing nanoparticles incorporated in a hybrid silica monolith with a high adsorption capacity. Moreover, it offers a valuable tool to monitor sulbactam, cefoperazone, and cefuroxime in whole blood from pregnant women with the final aim of guiding their administration. [ABSTRACT FROM AUTHOR]

Chien-Chih Wu,1,2 Chih-Hsun Tai,1 Wen-You Liao,2 Chi-Chuan Wang,2 Ching-Hua Kuo,2 Shu-Wen Lin,1,3 Shih-Chi Ku41Department of Pharmacy, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, Taiwan; 2School of Pharmacy, College of Medicine, National Taiwan University, Taipei, Taiwan; 3Graduate Institute of Clinical Pharmacy, College of Medicine, National Taiwan University, Taipei, Taiwan; 4Division of Chest Medicine, Department of Internal Medicine, National Taiwan University Hospital, Taipei, TaiwanCorrespondence: Shih-Chi KuDivision of Chest Medicine, Department of Internal Medicine, National Taiwan University Hospital, 7 Chung Shan S. Road, Taipei, TaiwanTel +886 22 356 2905Fax +886 22 358 2867Email scku1015@gmail.comBackground: Augmented renal clearance (ARC) is common in critically ill patients and could result in subtherapeutic antibiotic concentration. However, data in the Asian population are still lacking. The aim of this study was to explore the incidence and risk factors of ARC and its effect on β-lactam pharmacokinetics/pharmacodynamics (PK/PD) in Asian populations admitted to a medical ICU. In addition, we evaluated the appropriateness of using three estimated glomerular filtration (eGFR) formulas [Cockcroft–Gault (CG), Modification of Diet in Renal Disease (MDRD), and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI)] as screening tools.Methods: We measured 2-, 8-, and 24-hr creatinine clearance (CLCr) and calculated eGFR by using three formulas for each. ARC was defined as CLCr24hr >130 mL/min/1.73 m2. Concentrations at the mid-dosing interval and prior to the next dose were collected if patients received the β-lactam antibiotic of piperacillin/tazobactam, cefepime, and meropenem, to determine the PK/PD index of fT > MIC. Multiple logistic regression analysis was conducted to identify the risk factors for ARC. Pearson correlation coefficient and the Bland and Altman method were applied to assess the accuracy of CLCr2hr, CLCr8hr, and eGFR for predicting ARC.Results: Of 100 patients, 46 (46%) manifested ARC. Younger age (4MIC (33% vs 75%, p MIC (23% vs 69%, p4MIC (3% vs 25%, p

Staphylococcus aureus is among the pathogens capable of developing a broad spectrum of infections in human beings. In addition to the hospital, the bacterium is present in the community and has a high resistance to antibiotics, which is also increasing on an ongoing basis. Resistance to β-lactam antibiotic family is one of the concerns about the bacterium that has encountered the treatment of such infections with difficulty. Due to the increased resistance and importance of this bacterium, new strategies are needed to control this pathogen. One of these approaches is the use of medicinal plants, which has attracted many researchers in the last decade. Several studies have been carried out or are being designed using various herbs to find active ingredients to deal with this bacterium. The aim of this study was to present the antibacterial activity of different medicinal plants and the effects of their active ingredients on methicillin-resistant and methicillin-sensitive S. aureus and to clarify the pathway to further studies in this regard.

Background: The spread of KPC-producing Enterobacteriaceae has triggered a global public health concern, with KPC-2-positive strains being the most prevalent in China. We hereby studied the in vitro combined inhibitory activities of three kinds of β-lactam antibiotics and clavulanic acid at different concentrations against blaKPC-2-positive Klebsiella pneumoniae to explore the antimicrobial characteristics of these combinations and alternative therapeutic regimens for infections caused by blaKPC-2-positive K. pneumoniae strains. Materials and Methods: In this study, 153 clinically isolated blaKPC-2-positive K. pneumoniae strains from 19 provinces in China were collected from 2016 to 2018. Antimicrobial susceptibility testing of imipenem/clavulanic acid, meropenem/clavulanic acid, ceftazidime/clavulanic acid, and each antimicrobial agent alone was performed by broth microdilution technique according to the CLSI guidelines. The concentration ratios of β-lactam antibiotics to clavulanic acid were as follows: 1:1, 1:2, 1:4, 1:8, 1:16, 1:32. The antimicrobial susceptibility of the combinations was determined according to the breakpoints of Imipenem, meropenem, and ceftazidime established by the CLSI directives for Enterobacteriaceae. Results: The MICs of all three combinations gradually declined with increments in the proportion of clavulanic acid in the regimens, and the most significant decline in the MIC50 and MIC90 was seen in combinations at the concentration ratio of 1:1 (also 1:2 for meropenem/clavulanic acid). When the concentration of clavulanic acid was restricted to 4 mg/L, the susceptibility of more than 70% of the isolates to the regimens could be restored with imipenem MIC 2– 4 mg/L, meropenem MIC 2– 8 mg/L or ceftazidime MIC 8mg/L. However, the percentage decreased to 30 to 40% when the initial MIC level was higher. Conclusion: The highest combined inhibitory activity of β-lactam antibiotics/clavulanic acid at low concentration ratios against blaKPC-2-positive K. pneumoniae may offer a new way to optimize the effects of these antimicrobial regimens. [ABSTRACT FROM AUTHOR]

Emerging β-lactam antibiotic resistance necessitates the development of new therapeutic approaches. One approach to counteract this issue is the use of nanoparticles (NPs) for antimicrobial agent delivery. In this work, superparamagnetic MnFe2O4 NPs were synthesized via a simple co-precipitation method followed by coating with a SiO2 shell using tetraethoxysilane (TEOS) to prevent agglomeration and also increase the density of hydroxyl groups on the surface of MnFe2O4 NPs. The resulting MnFe2O4@SiO2 nanostructures were further functionalized with 3-aminopropyltriethoxysilane (APTES) to introduce NH2 groups on the surface of NPs for covalent grafting of ampicillin (AMP), β-lactam antibiotic. The MnFe2O4@AMP NPs proved to be highly effective for the eradication of Escherichia coli bacteria with a minimum inhibitory concentration (MIC) equivalent to 4 µg/mL of immobilized AMP, lowered by 50% compared to free AMP. The intrinsic multivalence effect of the nanostructures as well as the protection of the COO− group of the antibiotic from the attack of β-lactamase enzyme is believed to be responsible for enhanced efficiency of the hybrid compared to free AMP. [ABSTRACT FROM AUTHOR]

Bacteria express β-lactamase to counteract the bactericidal effects of β-lactam antibiotics, which are the most widely employed antibacterial drugs. In gram-negative bacteria, the expression of β-lactamase is generally regulated in response to the muropeptide that is generated from the peptidoglycan of the cell wall during β-lactam antibiotic challenge. The direct regulation of β-lactamase expression by β-lactams was recently reported in Vibrio parahaemolyticus , and this regulation is mediated by a two-component regulatory system that consists of the histidine kinase VbrK and the response regulator VbrR. VbrK directly recognizes β-lactam antibiotics using the periplasmic sensor domain (VbrKSD), a PF11884 Pfam family member, and it delivers the β-lactam signal to VbrR to induce the transcription of the β-lactamase gene. To determine the structural features of VbrKSD as the prototype of the PF11884 family and provide insights into the β-lactam antibiotic-binding mode of VbrKSD, we determined the crystal structure of VbrKSD at 1.65 Å resolution. VbrKSD folds into a unique curved rod-like structure that has not been previously reported in other families. VbrKSD consists of two domains (D1 and D2). The D1 domain contains two helix-decorated β-sheets, and the D2 domain adopts a helix-rich structure. VbrKSD features two terminal disulfide bonds, which would be the canonical property of the PF11884 family. In the VbrKSD structure, the L82 residue, which was previously shown to play a key role in β-lactam antibiotic recognition, forms a pocket along with its neighboring hydrophobic or positively charged residues. • The monomeric structure of the sensor domain of VbrK (VbrKSD) was determined. • VbrKSD consists of two domains and is shaped into a unique curved rod-like structure. • The PF11884 family, which includes VbrKSD, is characterized by cysteine residues. • The VbrK L82 residue that was shown to be required for penicillin binding forms a pocket. [ABSTRACT FROM AUTHOR]

Methicillin-resistant Staphylococcus aureus (MRSA) strains are distinct from general Staphylococcus strains with respect to the composition of the membrane, ability to form a thicker biofilm, and, importantly, ability to modify the target of antibiotics to evade their activity. The agr gene is an accessory global regulator of gram-positive bacteria that governs virulence or resistant mechanisms and therefore an important target for the control of resistant strains. However, the mechanism by which agr impacts resistance to β-lactam antibiotics remains unclear. In the present study, we found the Δagr mutant strain having higher resistance to high concentrations of β-lactam antibiotics such as oxacillin and ampicillin. To determine the influence of variation in the microenvironment of cells between the parental and mutant strains, fatty acid analysis of the supernatant, total lipids, and phospholipid fatty acids were compared. The Δagr mutant strain tended to produce fewer fatty acids and retained lower amounts of C16, C18 fatty acids in the supernatant. Phospholipid analysis showed a dramatic increase in the hydrophobic longer-chain fatty acids in the membrane. To target membrane, we applied several surfactants and found that sorbitan monolaurate (Span20) had a synergistic effect with oxacillin by decreasing biofilm formation and growth. These findings indicate that agr deletion allows for MRSA to resist antibiotics via several changes including constant expression of mecA, fatty acid metabolism, and biofilm thickening. [ABSTRACT FROM AUTHOR]

The aim of this study was to study the degradation of β-lactam antibiotics in aqueous solutions by ultrasonic along with UV/immobilized ZnO catalyst. The variables such as contact time, antibiotic concentration, and ZnO dose were studied according to the response surface methodology. In the optimum condition, the removal efficiency of 94.2% for PCG and 84.2% for CFX was obtained. The BOD5/COD ratio in the optimum condition increased from 0 to about 0.4. The quadratic and linear model was well fitted with test results (R2 = 0.871–0.996). The results showed that sonophotocatalytic process led to the effective degradation of the PCG and CFX and their enhanced biodegradability. [ABSTRACT FROM AUTHOR]

Metallo‐β‐lactamases (MBLs) are some of the best known β‐lactamases produced by common Gram‐positive and Gram‐negative pathogens and are crucial factors in the rise of bacterial resistance against β‐lactam antibiotics. Although many types of β‐lactamase inhibitors have been successfully developed and used in clinical settings, no MBL inhibitors have been identified to date. Nitrocefin, checkerboard and time‐kill assays were used to examine the enzyme behaviour in vitro. Molecular docking calculation, molecular dynamics simulation, calculation of the binding free energy and ligand‐residue interaction decomposition were used for mechanistic research. The behaviour of the enzymes in vivo was investigated by a mouse infection experiment. We showed that theaflavin‐3,3´‐digallate (TFDG), a natural compound lacking antibacterial activities, can inhibit the hydrolysis of MBLs. In the checkerboard and time‐kill assays, we observed a synergistic effect of TFDG with β‐lactam antibiotics against methicillin‐resistant Staphylococcus aureus BAA1717. Molecular dynamics simulations were used to identify the mechanism of the inhibition of MBLs by TFDG, and we observed that the hydrolysis activity of the MBLs was restricted by the binding of TFDG to Gln242 and Ser369. Furthermore, the combination of TFDG with β‐lactam antibiotics showed effective protection in a mouse Staphylococcus aureus pneumonia model. These findings suggest that TFDG can effectively inhibit the hydrolysis activity of MBLs and enhance the antibacterial activity of β‐lactam antibiotics against pathogens in vitro and in vivo. [ABSTRACT FROM AUTHOR]

The electrochemical behaviour of cefadroxil, a first-generation β-lactam antibiotic, was studied at glassy carbon electrodes in aqueous media over a wide range of pH. The first oxidation process is of the phenol moiety and follows an ECE mechanism, generating catechol and resorcinol derivatives as sub-products, which are then reduced and oxidized in subsequent cycles. The sulphur heteroatom present in the cyclic structure close to the β-lactam moiety is oxidized in two steps generating sulphoxide and sulphone. This process was identified from direct comparison with amoxicillin, which has a similar molecular structure, although they belong to different classes of β-lactam antibiotics. For amoxicillin, oxidation of the sulphur heteroatom occurred at more positive potentials, most likely due to structural difficulties in stabilizing the charged oxidized species. Formation of a complex between copper (II) and each of the antibiotics was studied by cyclic voltammetry. Finally, determination of cefadroxil in commercial samples was successfully carried out. • Electrochemical characterization of cefadroxil at glassy carbon in aqueous media • Oxidation of the phenol moiety by ECE mechanism generating catechol and resorcinol • Comparison between electrochemical profile of cefadroxil and amoxicillin • The phenol oxidation process was used to obtain a limit of detection of 0.3 μM. • Phenol oxidation was used to measure the amount of cefadroxil in commercial samples. [ABSTRACT FROM AUTHOR]

Abstract The emergence of antibiotic resistance has attracted the attention of scientists and scientific circles over the decades. β-Lactam antibiotics resistance is a worldwide therapeutic challenge in bacterial infections, mediated through several mechanisms of which mutations in Penicillin Binding Proteins (PBPs) are an important issue, making critical therapeutic problems in the human population. Accordingly, investigating the dynamic structures of mutant variants could result in a profound understanding of such a specific resistance. Therefore, this work investigated structural properties sampled by all-atom molecular dynamics (MD) simulations, umbrella sampling, and binding free energy calculations for both a wild-type and a cefotaxime-resistant T to S mutant of PBP1A. The T to S mutation significantly reduces the binding affinity of cefotaxime (a frequently clinically-administrated β-lactam antibiotic) as the PBP1A inhibitor. In the conventional MD simulations presented here, more fluctuations of the mutant's active site cleft margins were detected. The cleft of the mutant protein also opened remarkably more than the wild-type's cleft and displayed more flexibility. Thus, our findings have shown that flexibility of cleft margins of the active site in the mutant PBP1A immediately results in the catalytic cleft opening. In addition, binding free energy calculation suggests that reducing hydrophobic contacts and increasing the polar contribution in the binding energy may play an important role in cefotaxime resistance. Graphical abstract Conventional molecular dynamics simulations, binding free energy calculations, and umbrella sampling simulations were done to understand how the threonine to serine mutation at the catalytic site, affects the affinity of cefotaxime to penicillin binding protein. Image 1 Highlights • Conventional molecular dynamics simulations, binding free energy calculations, and umbrella sampling simulations were done to understand how the threonine to serine mutation at the catalytic site, affects the affinity of cefotaxime to penicillin binding protein. • The hydrophobic contacts are essential for the resistance of PBP1a to cefotaxime. • The flexibility of the binding pocket was increased in the mutant protein. • Both of the changes of the conformational enthalpy and entropy contribute to the threonine point mutation induced resistance of penicillin binding protein 1a against binding of cefotaxime. [ABSTRACT FROM AUTHOR]

Abstract Antimicrobial resistance (AMR) is an exceptional increasing challenge for human health; it is urgently need to develop novel leads that can be developed to clinically useful drugs. The idea to modify old class of antibiotics that has been a cornerstone of medical has been dramatically refreshed searching for ways to overcome antibiotic-resistant bacteria. A very interesting development is the implementation of carboranes in design of pharmacologically active molecules. A series of novel penicillin G analogs bearing lipophilic 1,2-dicarba- closo -dodecaborane (ortho -carborane), 1,7-dicarba- closo -dodecaborane (meta -carborane), or 1,12-dicarba- closo -dodecaborane (para -carborane) boron clusters, instead of the phenyl ring, were synthesized. The boron-cluster penicillin G analogs were obtained via amidation of 6-aminopenicillanic acid (6-APA) with N -succinimidyl active esters containing ortho- , meta -, or para -carborane Alternatively, analogs containing ortho- or para -carborane were synthesized using ortho - or para -carborane cluster acid chlorides. The compounds thus obtained were tested in vitro against gram-positive bacteria Staphylococcus aureus and gram-negative bacteria Klebsiella pneumoniae , Enterobacter cloacae , Acinetobacter baumanii , and Pseudomonas aeruginosa. The most potent inhibitor of gram-positive bacterial growth was compound 9 , bearing a para -carborane cluster. Compounds 7 and 8 bearing ortho - or metha -carborane, respectively, were less active against S. aureus. Graphical abstract Image 1 Highlights • A series of novel penicillin G analogs bearing ortho -/ meta -/ para -carborane were synthesized. • In vitro antibacterial activity was determined against gram-positive and gram-negative bacteria. • The most potent compound 9 displayed MIC 64 μg/mL against S. aureus ATCC 25923. • Low toxicity for the compounds 7 – 9 in the cell line used was observed. [ABSTRACT FROM AUTHOR]

β-Lactam antibiotics are one of the most clinical importance in human and veterinary medicine because they are used for both preventive and therapeutic purposes against several gram-positive, gram-negative, and anaerobic organisms. In this study, it was confirmed that β-lactams (81.1%) were found to be significantly prescribed the most among 74 farms in 5 integrated broiler operations, and single prescription (84.6%), 2-day (41.5%) or 3-day (40.0%) administration, and 15 to 22 d of age (67.7%) administration was significantly higher in the farms (P < 0.05). Among the E. coli isolated from 74 farms in 5 integrated broiler operations, β-lactam-resistant E. coli isolates were detected more frequently in fecal sample (94.6%) than in dust sample (60.8%) (P < 0.05). The prevalence of MDR in β-lactam-resistant isolates, ranging from 88.1 to 96.5%, was significantly higher than that in non–β-lactam-resistant isolates (P < 0.05), without significant differences among operations. Of 466 β-lactam-resistant isolates, 432 (92.7%) isolates harbored β-lactamase genes. The non–extended-spectrum β-lactamase (ESBL) gene bla TEM-1 (81.8%) showed the highest prevalence among isolates, followed by the non-ESBL gene bla TEM-135 (6.4%) (P < 0.05). Five ESBL genes, SHV-12, OXA-1, CTX-M-27, CTX-M-55, and CTX-M-65, were found in 0.9 to 6.0% of the isolates. The pAmpC gene bla CMY-2 was detected in 17 isolates (3.6%). These results suggest that feces and dust are important reservoirs of antimicrobial-resistant bacteria, highlighting the need to strengthen farm management regulations, such as cleaning, disinfection, and litter disposal and to reduce the use of antibiotics in broiler operations. [ABSTRACT FROM AUTHOR]

The emergence of multi-drug-resistant bacteria, coupled with the lack of new antibiotics in development, is fast evolving into a global crisis. New strategies utilizing existing antibacterial agents are urgently needed. We propose one such strategy in which four outmoded β-lactam antibiotics (ampicillin, carbenicillin, cephalothin and oxacillin) and a well-known antiseptic (chlorhexidine di-acetate) were fashioned into a group of uniform materials based on organic salts (GUMBOS) as an alternative to conventional combination drug dosing strategies. The antibacterial activity of precursor ions (e.g., chlorhexidine diacetate and β-lactam antibiotics), GUMBOS and their unreacted mixtures were studied with 25 clinical isolates with varying antibiotic resistance using a micro-broth dilution method. Acute cytotoxicity and therapeutic indices were determined using fibroblasts, endothelial and cervical cell lines. Intestinal permeability was predicted using a parallel artificial membrane permeability assay. GUMBOS formed from ineffective β-lactam antibiotics and cytotoxic chlorhexidine diacetate exhibited unique pharmacological properties and profound antibacterial activity at lower concentrations than the unreacted mixture of precursor ions at equivalent stoichiometry. Reduced cytotoxicity to invasive cell types commonly found in superficial and chronic wounds was also observed using GUMBOS. GUMBOS show promise as an alternative combination drug strategy for treating wound infections caused by drug-resistant bacteria.

To combat the serious issue of increasing global antibiotic resistance, new antimicrobial therapies are urgently required. As one alternative, previously used antibiotics are being investigated for use in combination with more modern antibiotics including antimicrobial peptides. Towards this goal, 7-aminocephalosporanic acid, the precursor to the conventional β-lactam antibiotic, cephalosporin, and the related compound, 7-aminodesacetoxycephalosporanic acid, were each chemically modified to enable their use in solid phase peptide synthesis for covalent conjugation via their 7-amino group and a glycolic linker to the N-terminus of a series of cationic antimicrobial peptides, MSI-78, CA(1-7)M(2-9)NH2 and des-Chex1-Arg20. Chemically functionalized Cα-Fm-protected 7-aminocephalosporanic acid and 7-aminodesacetoxycephalosporanic acid building blocks were separately prepared and attached by their 7-amino group to the N-terminus of each peptide on the solid phase via a glutaric anhydride linker. The resulting conjugated AMPs were assessed for antibacterial activity against a panel of six Gram-negative bacteria, including clinically isolated multi-drug resistant (MDR) pathogens. Only the conjugated MSI-78 analogues displayed significant activity against Acinetobacter baumannii and MDR A. baumannii 156 and enhanced activity against Klebsiella pneumoniae. Further work is required to optimize the conjugation of AMPs to 7-cephalosporanic acid and/or 7-aminodesacetoxycephalosporanic acid to universally induce an enhanced effect on killing of drug sensitive and MDR bacterial strains that are common causes of hospital-acquired infections. [ABSTRACT FROM AUTHOR]

Ampicillin belongs to the class of beta-lactam antibiotics, which corresponds the most prescribed antibiotics in medicine. This justifies the importance of elucidating the effect of several variables for the synthesis process (pH, temperature, co-solvent) on the behavior of the compounds involved in the enzymatic reaction. This paper aims to present new ampicillin solubility data in aqueous medium and the characterization of the solid phase of the antibiotic. In the phase equilibrium experiments it was considered the effect of pH (3 up to 7.5), temperature (283.15 K up to 298.15 K) and the ethanol concentration in the aqueous solution (varying between 0 and 70 wt% ethanol). The solubility curves deviate from U-shape solubility curves with respect to pH in the range of 0–70 wt%. This is due to ampicillin anhydrous becomes trihydrated molecule in the solid phase at alkaline pH region, changing the antibiotic properties significantly. This change in crystalline structure was confirmed by characterization of antibiotic solid phase carried out from thermogravimetric (TGA), Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) analyses. Dissociation constants have also been measured at the studied values of temperature and ethanol composition, using potentiometric titration. Finally, a thermodynamic model considering the ideal solution was applied to describe mathematically the solubility curves measured close to experimental uncertainties. [ABSTRACT FROM AUTHOR]

The emergence of multidrug-resistant bacteria contributes to the necessity of developing novel infection treatment approaches. This study was designed to evaluate the antimicrobial and wound healing activities of platelet-rich plasma (PRP) in combination with β-lactams (ampicillin and/or oxacillin) for the application on methicillin-resistant Staphylococcus aureus (MRSA)-infected skin. PRP was collected from the peripheral blood of healthy donors. The anti-MRSA activity was tested through a growth inhibition curve, colony-forming unit (CFU), and SYTO 9 assay. The PRP incorporation lowered the minimum inhibitory concentration (MIC) of ampicillin and oxacillin against MRSA. The combination of β-lactams together with PRP showed a three-log CFU reduction of MRSA. The major components of PRP for eliminating MRSA were found to be the complement system and iron sequestration proteins, according to the proteomic analysis. The adhesive bacterial colony in the microplate was decreased from 2.9 × 107 to 7.3 × 105 CFU after the treatment of cocktails containing β-lactams and PRP. The cell-based study indicated that keratinocyte proliferation was stimulated by PRP. The in vitro scratch and transwell experiments revealed that PRP improved keratinocyte migration. In the MRSA-infected mouse skin model, PRP appeared to show a synergistic effect for wound area reduction by 39% when combined with β-lactams. The MRSA burden in the infected area was lessened two-fold after topical administration of the combined β-lactams and PRP. PRP inhibited macrophage infiltration in the wound site to shorten the inflammatory phase and accelerate the initiation of the proliferative phase. No skin irritation was detected with the topical delivery of this combination. Our findings suggested that β-lactams plus PRP was applicable to alleviate the problems associated with MRSA via dual antibacterial and regenerative activities. [Display omitted] • We aimed to evaluate the antimicrobial and healing activity of PRP on skin. • The combination of PRP with βlactams demonstrated a synergistic anti-MRSA effect. • PRP promoted keratinocyte proliferation and migration for skin wound healing. • Topical treatment of β-lactams plus PRP did not cause adverse effects on skin. [ABSTRACT FROM AUTHOR]

The problem of determining the formation of complexes of β-lactam antibiotics with cyclodextrins (CDs) and the interactions involved in this process were addressed by machine learning on multispectral images. Complexes of β-lactam antibiotics, including cefuroxime axetil, cefetamet pivoxil, and pivampicillin, as well as CDs, including αCD, βCD, γCD, hydroxypropyl-αCD, methyl-βCD, hydroxypropyl-βCD, and hydroxypropyl-γCD, were prepared in all combinations. Thermograms confirming the formation of cyclodextrin complexes were obtained using differential scanning calorimetry. Transmission Fourier-transform infrared (tFTIR) and complementary attenuated total reflectance FTIR (ATR) coupled with machine learning were techniques chosen as a nondestructive alternative. The machine learning algorithm was used to determine the formation of complexes in samples using solely their tFTIR and ATR spectra at the prediction stage. Parameterized method 7 (PM7) was used to support the analysis by molecular modeling of the complexes. The model developed through machine learning properly distinguished samples with formed complexes form noncomplexed samples with a cross-validation accuracy of 90.4%. Analysis of the contribution of spectral bands to the model indicated interactions of ester groups of β-lactam antibiotics with CDs, as well as some interactions of cephem ring in cefetamet pivoxil and penam moiety in pivampicillin. Molecular modeling with PM7 helped to explain experimental results and allowed to propose possible binding modes.

The impact of the antibiotic ampicillin (AMP) on the metabolic and kinetics of denitrification process as well as the sludge ability for oxidizing it was evaluated in batch assays. Denitrifying reference assays with acetate-C and nitrate-N (C/N ratio of 1.1) were conducted for establishing the metabolic and kinetic performance of the denitrifying sludge. Assays amended with 10 mg AMP-C L were also performed. In reference assays, acetate and nitrate consumption efficiencies of 100% with a total conversion to HCO and N were achieved within 1.5 h. When 10 mg AMP-C L was added, total and simultaneous consumption of nitrate-N, acetate-C, and AMP-C was achieved within 12 h. The substrates were completely reduced to N and oxidized to HCO , respectively. No nitrite-N was registered at the end of culture. AMP caused a reversible inhibitory effect on specific nitrate and acetate consumption and N production rates. Complete consumption and mineralization of AMP associated to nitrate reduction to N were achieved. This work provides the first evidences on the metabolic and kinetic performance of a denitrifying sludge exposed to AMP. These results might be considered for proposing useful wastewater treatments where β-Lactam antibiotics can be present. [ABSTRACT FROM AUTHOR]

Excitotoxicity is a major pathological trigger of neurodegenerative diseases like amyotrophic lateral sclerosis. This process is caused by excessive release of the transmitter glutamate that overwhelms the capacity of astroglia transporters to maintain a low extracellular level of this aminoacid and strongly stimulates neurons. Using an in vitro model of rat organotypic spinal slice culture, we explored if the excitotoxicity caused by the potent glutamate analogue kainate, widely employed as a paradigm to evoke neurotoxicity in the central nervous system, was prevented by the antibiotic ceftriaxone known to enhance glutamate transporter expression. We also tested if excitotoxicity was made worse by inhibiting glutamate uptake with dl-threo-β-benzyloxyaspartate (TBOA). These experiments were aimed at clarifying the relative contribution to neurotoxicity by kainate-activation of glutamate receptors or kainate-mediated release of glutamate. Neither ceftriaxone nor TBOA alone had adverse effects. Ceftriaxone (10 μM; 3 days) significantly decreased delayed cell death induced by kainate (100 μM; 1 h) and limited neuronal damage especially to motoneurons. This effect was associated to stronger astrocytic immunostaining of the glutamate transporter GLT-1. Conversely, pharmacological inhibition of glutamate uptake with TBOA was per se unable to induce neurotoxicity, yet it intensified cell death evoked by kainate. These data indicate that kainate-mediated glutamate release was critical to damage neurons, an effect prevented by up regulating glutamate uptake. These data suggest that modulating glutamate uptake is an important strategy to preserve neuronal networks. [ABSTRACT FROM AUTHOR]

The objective of this study was to describe the effect of therapeutic drug monitoring (TDM) and dose adjustments of β-lactam antibiotics administered to critically ill patients undergoing continuous renal replacement therapy (CRRT) in a 30-bed tertiary intensive care unit (ICU). β-Lactam TDM data in our tertiary referral ICU were retrospectively reviewed. Clinical, demographic and dosing data were collected for patients administered β-lactam antibiotics while undergoing CRRT. The target trough concentration range was 1–10× the minimum inhibitory concentration (MIC). A total of 111 TDM samples from 76 patients (46 male) with a mean ± standard deviation age of 56.6 ± 15.9 years and weight of 89.1 ± 25.8 kg were identified. The duration of antibiotic therapy was between 2 days and 42 days. TDM identified a need for dose modification of β-lactam antibiotics in 39 (35%) instances; in 27 (24%) samples, TDM values resulted in decreasing the prescribed dose of β-lactam antibiotic whereas an increase in the prescribed dose occurred in 12 (11%) cases. In patients treated for hospital-acquired pneumonia and primary or secondary bacteraemia, the dose was required to be decreased in 10/25 (40%) and 7/46 (15%) cases, respectively, to attain target concentrations. β-Lactam TDM is a useful tool for guiding drug dosing in complex patients such as those receiving CRRT. Although over one-third of patients manifested concentrations outside the therapeutic range, most of these CRRT patients had excessive β-lactam concentrations. [ABSTRACT FROM AUTHOR]

β-lactam antibiotics represent a novel direction in the chemotherapy of tuberculosis that brings the peptidoglycan layer of the complex mycobacterial cell wall in focus as a therapeutic target. Peptidoglycan stability in Mycobacterium tuberculosis, especially during infection, relies on the nonconventional peptide cross-links formed by l,d-transpeptidases. These enzymes are known to be inhibited by β-lactams, primarily carbapenems, leading to a stable covalent modification at the enzyme active site. A panel of 16 β-lactam antibiotics was characterized by inhibition kinetics, mass spectrometry, and x-ray crystallography to identify efficient compounds and study their action on the essential transpeptidase, LdtMt2. Members of the carbapenem class displayed fast binding kinetics, but faropenem, a penem type compound showed a three to four time higher rate in the adduct formation. In three cases, mass spectrometry indicated that carbapenems may undergo decarboxylation, while faropenem decomposition following the acylation step results in a small 87 Da β-OH-butyryl adduct bound at the catalytic cysteine residue. The crystal structure of LdtMt2 at 1.54 Å resolution with this fragment bound revealed that the protein adopts a closed conformation that shields the thioester bond from the solvent, which is in line with the high stability of this dead-end complex observed also in biochemical assays. Database Structural data are available in Protein Data Bank under the accession numbers and . [ABSTRACT FROM AUTHOR]

This study evaluates the treatment of the antibiotic cloxacillin (CLX) in water by means of electrochemical oxidation, TiO photocatalysis, and the photo-Fenton system. The three treatments completely removed cloxacillin and eliminated the residual antimicrobial activity from synthetic pharmaceutical wastewater containing the antibiotic, commercial excipients, and inorganic ions. However, significant differences in the degradation routes were found. In the photo-Fenton process, the hydroxyl radical was involved in the antibiotic removal, while in the TiO photocatalysis process, the action of both the holes and the adsorbed hydroxyl radicals degraded the pollutant. In the electrochemical treatment (using a Ti/IrO anode in sodium chloride as supporting electrolyte), oxidation via HClO played the main role in the removal of CLX. The analysis of initial by-products showed five different mechanistic pathways: oxidation of the thioether group, opening of the central β-lactam ring, breakdown of the secondary amide, hydroxylation of the aromatic ring, and decarboxylation. All the oxidation processes exhibited the three first pathways. Moreover, the aromatic ring hydroxylation was found in both photochemical treatments, while the decarboxylation of the pollutant was only observed in the TiO photocatalysis process. As a consequence of the degradation routes and mechanistic pathways, the elimination of organic carbon was different. After 480 and 240 min, the TiO photocatalysis and photo-Fenton processes achieved ∼45 and ∼15 % of mineralization, respectively. During the electrochemical treatment, 100 % of the organic carbon remained even after the antibiotic was treated four times the time needed to degrade it. In contrast, in all processes, a natural matrix (mineral water) did not considerably inhibit pollutant elimination. However, the presence of glucose in the water significantly affected the degradation of CLX by means of TiO photocatalysis. [ABSTRACT FROM AUTHOR]

Alternative solutions need to be developed to overcome the growing problem of multi-drug resistant bacteria. This study explored the possibility of creating complexes of antibiotics with metal ions, thereby increasing their activity. Analytical techniques such as isothermal titration calorimetry and nuclear magnetic resonance were used to examine the structure and interactions between Cu(II), Ag(I) or Zn(II) and β-lactam antibiotics. The metal-β-lactam complexes were also tested for antimicrobial activity, by micro-broth dilution and disk diffusion methods, showing a synergistic increase in the activity of the drugs, and enzymatic inhibition assays confirming inhibition of β-lactamases responsible for resistance. The metal-antibiotic complex concept was proven to be successful with the activity of the drugs enhanced against β-lactamase-producing bacteria. The highest synergistic effects were observed for complexes formed with Ag(I). [ABSTRACT FROM AUTHOR]

We developed a lateral flow immunoassay (LFIA) based on a sensitive and specific monoclonal antibody against piperacillin (PIP) with a half-maximal inhibitory concentration of 0.136 ng/mL for PIP detection in milk and milk powder. After the conditions were optimized, the visual limit of detection of LFIA was 2 ng/mL and 5 ng/g, and the cut-off value was 5 ng/mL and 20 ng/g in milk and milk powder, respectively. In the recovery assay of the spiked samples, the results of the LFIA strips were obtained within 10 min and were consistent with those obtained from indirect competitive enzyme-linked immunosorbent assay (ic-ELISA). Therefore, our developed method is a rapid, sensitive, and reliable tool for the detection of PIP in milk and milk powder. • A sensitive and specific monoclonal antibody against piperacillin (PIP) was prepared. • A lateral flow immunoassay (LFIA) was developed for PIP rapid detection. • The visual limit of detection of LFIA was 2 ng/mL and 5 ng/g in milk and milk powder. • The developed LFIA is a reliable tool for PIP detection in milk samples. [ABSTRACT FROM AUTHOR]

The β-lactam antibiotics are the most effective medicines for treating bacterial infections. Resistance to them, particularly through the production of β-lactamases, which can hydrolyse all kinds of β-lactams, poses a threat to their continued use. The synthesised flavone and coumarin based isoxazole derivatives have the potential to be used as broad-spectrum inhibitors of the mechanistically different serine-(SBL) and metallo-β-lactamases (MBL). The synthesised compounds were discovered as potent β-lactamase inhibitors using molecular docking and in silico pharmacokinetic analysis. We studied the binding of chemically synthesised inhibitors to clinically significant β-lactamases of class A, B, and C using biophysical and biochemical approaches, and computational analyses. These molecules follow Lipinski's rule of five and have acceptable solubility, permeability, and oral bioavailability. These molecules were found to be non-toxic and non-carcinogenic. MIC results suggest that these molecules restore the antibiotic efficacy against class A, B, and C β-lactamases. Kinetics data showed that these molecules reduce the catalytic efficiency of clinically relevant class A, B, and C β-lactamases. Fluorescence study showed significant interaction between these flavone-/coumarin-based isoxazole derivatives and class A/B/ C β-lactamases. This study showed promising effect of these new generation compounds as broad spectrum β-lactamase inhibitors of both SBLs and MBLs.Communicated by Ramaswamy H. Sarma.

Artemisinin (ART) and its derivatives artesunate (AS), dihydroartemisinin (DHA) are a group of drugs containing a sesquiterpene lactone used to treat malaria. Previously, AS was shown to not have antibacterial activity but to significantly increase the antibacterial activities of β-lactam antibiotics against E. coli. Herein, molecular docking experiments showed that ART, AS and DHA could dock into AcrB very well, especially DHA and AS; both DHA and AS had the same docking pose. The affinity between AS and AcrB seemed weaker than that of DHA, while the succinate tail of AS, which was like a “bug”, could extend in the binding pocket very well. Imitating the parent nucleus of DHA and the succinate tail of AS, twenty-one DHA derivatives 4a–u were designed and synthesized. Among them, seventeen were new compounds. The synergistic effects against E. coli AG100A/pET28a-AcrB showed among the new structures 4k, 4l, 4m, 4n, and 4r exhibited significant synergism with β-lactam antibiotics although they had no direct antibacterial activities themelves. The bacterial growth assay showed that only 4k in combination with ampicillin or cefuroxime could totally inhibit bacterial growth from 0 to 12 h, demonstrating that 4k had the best antibacterial enhancement effect. In conclusion, our results provided a new idea and several candidate compounds for antibacterial activity enhancers against multidrug resistant E. coli.

The aim of this work was to compare the composition of a complex and soluble culture medium to eight other media described in the literature through the batch cultivation in a conventional bench-scale bioreactor for the production of cephamycin C by a wild strain of Streptomyces clavuligerus. The proposed medium resulted in an antibiotic production 1.5 to 7.5 times higher than the other culture media.

[Display omitted] • Fourty-eight 1,2,4-triazole-3-thione compounds with an arylalkyl moiety at position 4 are reported. • Several analogues were broad-spectrum inhibitors of clinically important MBLs. • Several analogues restored meropenem activity on VIM-1/4-producing clinical isolates. • The binding mode of three compounds to VIM-2 was studied by molecular modelling. Metallo-β-lactamases (MBLs) represent an increasingly serious threat to public health because of their increased prevalence worldwide in relevant opportunistic Gram-negative pathogens. MBLs efficiently inactivate widely used and most valuable β-lactam antibiotics, such as oxyiminocephalosporins (ceftriaxone, ceftazidime) and the last-resort carbapenems. To date, no MBL inhibitor has been approved for therapeutic applications. We are developing inhibitors characterized by a 1,2,4-triazole-3-thione scaffold as an original zinc ligand and few promising series were already reported. Here, we present the synthesis and evaluation of a new series of compounds characterized by the presence of an arylalkyl substituent at position 4 of the triazole ring. The alkyl link was mainly an ethylene, but a few compounds without alkyl or with an alkyl group of various lengths up to a butyl chain were also synthesized. Some compounds in both sub-series were micromolar to submicromolar inhibitors of tested VIM-type MBLs. A few of them were broad-spectrum inhibitors, as they showed significant inhibitory activity on NDM-1 and, to a lesser extent, IMP-1. Among these, several inhibitors were able to significantly reduce the meropenem MIC on VIM-1- and VIM-4- producing clinical isolates by up to 16-fold. In addition, ACE inhibition was absent or moderate and one promising compound did not show toxicity toward HeLa cells at concentrations up to 250 μM. This series represents a promising basis for further exploration. Finally, molecular modelling of representative compounds in complex with VIM-2 was performed to study their binding mode. [ABSTRACT FROM AUTHOR]